rivers and streams final exam

Question 1

What is the hydrologic cycle?

Answer 1

It is how the water on earth rotates among different processes from the sea to the atmosphere to the land.

Question 2

What is a permanent stream?

Answer 2

A permanent stream is one that lies below the table water line.

Question 3

What is an ephemeral stream?

Answer 3

An ephemeral stream is one that lies above the table water line

Question 4

What is a braided stream?

Answer 4

A stream that has inter-fingering branch streams crisscrossing

Question 5

What is a meandering stream?

Answer 5

A snake like stream that has kinks and loops

Question 6

What is a point bar and cut bank and how do they form?

Answer 6

A point bar - area of deposition, corner of a meander, forms due to high velocity engaging a corner
a cut bank - area of erosion, forms due to the stream hitting the edge of the land causing a meander neck, which eventually erode due to constant erosion

Question 7

Where does erosion and deposition occur along a meandering stream?

Answer 7

A point bar creates deposition while a cut bank creates erosion

Question 8

How does a floodplain form?

Answer 8

Flood plains form when rivers erode their own banks and redeposit the eroded material downstream. They form due to the action of the river until it becomes a flat floodplain as a result of over bank deposition.

Question 9

How do deltas form?

Answer 9

Deltas form in result of the low course of the river slowing down and the stream entering standing waters. The stream will then divide into multiple tributaries that go into the ultimate base level

Question 10

What is a drainage basin?

Answer 10

One river acting as a father river of other branching streams that flow into it, not like a braided stream

Question 11

How is sediment transported in rivers?

Answer 11

The river can carry specific types of loads depending on its velocity, competence, and capacity.

Question 12

What is discharge?

Answer 12

Discharge is the amount of water a given stream can hold

Question 13

what is a hydrograph?

Answer 13

a graph that tracks the rainfall/discharge from floods over time

Question 14

How is discharge related to stream size?

Answer 14

The two are related because certain streams can only hold how much the can fit. So for example, one stream may have a larger discharge than a smaller stream based on SIZE

Question 15

How does discharge effect flood events?

Answer 15

Discharge affects flood events overflowing the given amount a river can actually hold

Question 16

Difference between competence and capacity?

Answer 16

Competence is the size of particle a river can move. Capacity is the amount of those particles.

Question 17

How is the energy of the stream related to the size of particles it can carry and deposit?

Answer 17

A stream’s velocity and size can affect the type of load it can move throughout. If the energy is low, then it may not be able to move large boulders and pebbles but can move silt and clay (vice versa)

Question 18

Why are large boulders the size of houses able to be moved during a flood?

Answer 18

Boulders can be moved during a flood because the water amount has increased and when there is more water on a given gradient, the energy level can be increased due to the velocity increasing. In result, the capacity and competence increased

Question 19

What is the difference between an alluvial fan and a delta?

Answer 19

delta’s form at the lower course of a stream and break of into an ocean (or base level). An alluvial fan forms on dry land while deltas form when entering water

Question 20

What is an alluvial fan?

Answer 20

a triangle shape/cone shaped deposit in result from stream deposits usually on dry land

Question 21

What triggers flooding?

Answer 21

Heavy rainfall, snow melting off, or failure of a dam or levee

Question 22

Costliest and most common natural hazard, more water coming down a channel than it can actually hold

Answer 22

flood

Question 23

smaller and short lived floods; intense rain event in smaller area, flood occurs after rain event; doesn’t affect areas down stream

Answer 23

upstream floods

Question 24

Long lived flood; huge amount of water; large river systems involved; adds up flooding in tributaries; more devastating damage

Answer 24

downstream floods

Question 25

flood where water rises rapidly with little warning; the ground in impermeable that it collects water easily

Answer 25

flash flood

Question 26

what causes flash floods

Answer 26

intense rainfall or dam failures - can be destructive

Question 27

barrier that restricts the movement of rivers and narrows the channels; increases depth in channel

Answer 27

Levees

Question 28

How do urban areas deal with flooding?

Answer 28

Since there is no groundwater to soak up the water, it drains off and are very short lived floods (upstream)

Question 29

How do we control floods

Answer 29

Create levees, put most important buildings away from flood plain, stop developing in floodplain, urbanization

Question 30

Some ways for flood hazard mitigation?

Answer 30

Restore the channel; determine where water will be different